1. Reducing the impact of IXP maintenance Will Hargrave // LONAP will@lonap.net

2. What is an IXP? A switched fabric for interconnecting networks BGP is the control plane for network operators to signal reachability What happens to production traffic when an IXP operator does maintenance?

3. ISP router A IXP Switches 192.0.1.2 192.0.1.3 A typical IXP BGP Session ISP router B

4. ISP router A ISP router B IXP Switches 192.0.1.2 192.0.1.3 Maintenance BGP Session

5. 192.0.1.2 192.0.1.3 Waiting for BGP holdtimers… BGP Session Where’s my peer? Traffic blackholed here  ISP router A ISP router B

6. IXP Switches 192.0.1.2 192.0.1.3 90 to 180 seconds later…. BGP Session Holdtimer expired ISP router A ISP router B

7. Improving the experience In many cases, IXP switch maintenance causes 90seconds+ blackholing of production traffic We are doing things the wrong way round! Solution: 1.At the start of the maintenance window, tear down the control plane! 2.Wait for traffic to diminish (3-5 minutes) 3.Now do your maintenance How to tear down the control plane? Answer: L4 ACLs on IXP port!

8. L4 ACLs on IXP entry DenyBGPv4e { if { source-address 5.57.80.0/22; protocol tcp; source-port 179; } then { deny; } entry DenyBGPv4i { if { source-address 5.57.80.0/22; protocol tcp; destination-port 179; } then { deny; } entry DenyBGPv6e { Your IXP subnet Block in both directions, otherwise sessions will re-establish Obviously repeat this for IPv6 too

9. End We tested this during two recent LONAP maintenances with success. Questions? Comments? Will Hargrave will@lonap.net